目录
一、关系代数Relational Algebra
1. 基本运算
a. 选择运算(Select Operation)
b. 投影运算(Project Operation)
组合
c. 并运算(Union Operation)
d. 集合差运算(Set Difference Op…
反射 Activator.CreateInstance
class Program
{static void Main(string[] args){//反射Type t typeof(Student);object o Activator.CreateInstance(t, 1, "FJ");Student stu o as Student;Console.WriteLine(stu.Name);//动态编程dynamic stu2 Activator.Cre…